Multiple socket terminal strip for terminal junction module

ABSTRACT

A plurality of stamped and formed cylindrical contact sockets are integral with a metallic bus strip and extend away from corresponding circular openings within the bus strip with a leading edge spaced from a drawn lip defining the circular openings. Each socket is connected to the strip by a connecting strap extending from one side of the socket to a side edge of the strip and an integral supporting leg extends from the leading edge of each socket on the side opposite the connecting strap toward the respective openings. A terminal pin retention spring surrounding each socket prevents removal of an inserted contact terminal pin and the removal force is transmitted directly from the socket body through the leg to the bus strip to resist socket deformation.

Uited States Patent 1 Hartwell et al.

[ 1 May 8, 1973 [54] MULTIPLE SOCKET TERMINAL STRIP FOR TERMINAL JUNCTION MODULE [75] Inventors: Ronald Groff Hartwell, Hummelstown; Arley Keener Miller, Middletown, both of Pa.

[52] U.S. Cl. ..339/l9, 339/65, 339/242,

339/262, 339/198 R [51] Int. Cl. ..H0lr 31/08 [58] Field of Search .339/19, 198 R, 198 C,

339/198 E, 198 G, 198 GA, 198 H, 198 J, 198 L, 198 S, 198 P, 198 M, 198 N, 65, 66 R, 66 M, 66 T, 258 R, 258 P, 242, 219 R, 192 R, 22 R, 22 B, 262, 256 R; 29/630 B [56] References Cited UNITED STATES PATENTS 1,951,168 3/1934 Roth ..339/198 R 3,594,714 7/1971 Paullus et al. ..339/242 3,315,219 4/1967 Brinser et al ..339/198 R FOREIGN PATENTS OR APPLICATIONS 1,009,358 11/1965 Great Britain .339/258 R nth OTHER PUBLICATIONS Kryzaninsky, IBM Tech. Disc. 2-1972 Barrel Connector Vol. 14 No. 9, p. 2599.

Ciofii, IBM Tech. Disc. 3-1966 Connector Vol. 8 N0. 10, p. 1327.

Germany ..339/258 R Primary Examiner-Marvin A. Champion Assistant Examiner-Robert A. I-Iafer AttorneyWilliam J. Keating et al.

1 1 ABSTRACT A plurality of stamped and formed cylindrical contact sockets are integral with a metallic bus strip and extend away from corresponding circular openings within the bus strip with a leading edge spaced from a drawn lip defining the circular openings. Each socket is connected to the strip by a connecting strap extending from one side of the socket to a side edge of the strip and an integral supporting leg extends from the leading edge of each socket on the side opposite the connecting strap toward the respective openings. A terminal pin retention spring surrounding each socket prevents removal of an inserted contact tenninal pin and the removal force is transmitted directly from the socket body through the leg to the bus strip to resist socket deformation.

9 Claims, 7 Drawing Figures PATENTED-HAY 81m SHEET 1 or 4 H R A R w R Dr (PRIQR ART) MULTIPLE SOCKET TERMINAL STRIP F OR TERMINAL JUNCTION MODULE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a terminal junction wiring module employing a cluster of integral, stamped and formed electrical contact sockets carried commonly by a metallic bus strip and, more particularly, to such a terminal strip, in which each socket carries a terminal pin retention spring for retaining an inserted terminal pin.

2. Description of the Prior Art Terminal junction wiring systems employ single or multiple modules in the form of a housing of rigid insulating material, conventionally of rectangular configuration, incorporating means for physically mounting the housing to a support, and wherein a plurality of such housings may be mounted in side-by-side fashion, depending upon the number of electrical interconnections being made. Each housing is provided with a plurality of contact-receiving cavities which extend in parallel spaced fashion within the housing and extend inwardly from an open side thereof. conventionally, a cluster of closely spaced and aligned electrical contact sockets are supported in a common manner by a metallic bus strip such that the cylindrical contact sockets are inserted within respective contact receiving cavities or passageways and means are provided for preventing the extraction of the bus strip carrying the contact sockets from the housing. Further, in making the electrical interconnections, male contact terminals in the form of cylindrical pins are inserted within the individual contact sockets. In order to maintain engagement between the inserted cylindrical contact terminal pins and the contact sockets which receive the same, conventionally the sockets and the inserted pins carry mutually engageable terminal pin retention means resisting withdrawal or retrograde movement of the pins. Due to the fact that relatively large forces are sometimes exerted on the formed electrical interconnections tending to remove the pins from the sockets, the sockets must be constructed in such a manner as to resist deformation due to the withdrawal forces. Further, in order to allow selective removal or disengagement of an inserted contact terminal pin with its pin receiving socket, the pin retaining means must be such that easy and positive disengagement release of the pin from the socket may readily occur. Further, since the socket and the inserted pin are surrounded by, and are located within, the individual passageways or recesses of the housing, means must be provided for permitting a release tool to contact the retention means for the individual sockets to permit ready release of the retention means.

Reference to FIGS. 1 and 2 illustrates a portion of a known terminal strip for use in a terminal junction module of the type to which the present invention is directed. The perspective view of FIG. 1, and the sectional view of FIG. 2, illustrate the manner in which each socket of the cluster is constructed, and its manner'of attachment to the common bus strip which supports and electrically connects the multiple pin receiving sockets. The prior art terminal strip, as illustrated in FIGS. 1 and 2, employs the pin retention means of the type found in U. S. Pat. No. 2,513,305 to C. E. Gagnier et al. issuing July 4, I950. It should be stated that the present invention is also directed to an improved terminal strip construction wherein a cluster of electrical contact sockets are supported by and extend from a metallic bus strip and in which the sockets each receive an inserted terminal pin and retain it by a concentrically carried cylindrical retention spring generally similar to that of the Gagnier et al. U.S. Pat. No. 2,513,305. Reference may be had to U.S. Pat. No. 2,5 l3,305 as well as FIGS. 3-7 inclusive of the present application directed to the improved terminal strip of the present invention, for a full understanding of the common operating principle of the prior art terminal strip construction and that of the instant invention.

Essentially, the prior art terminal strip is characterized by a thin metallic bus strip 10 of which only a portion of the strip is shown, the strip 10 being provided along its length with a series of spaced circular openings 12 to which the flared end 14 of a cylindrical electrical contact socket 16 is brazed. The socket is inserted into the opening 12 to the extent permitted by flared end 14, with the sockets 16 extending away from the bus strip 10 and generally at right angles thereto. Not only does the necessity of forming the socket 16 separate from the bus strip, and inserting the separately formed socket 16 within the opening of the bus strip and the brazing of the same required as at 18 complicate the structure, but in addition the socket must be screw machined and subsequently altered to provide openings 18 and 20. Further, a spring retention rim 22 must be machined from the outer surface of the cylindrical socket 16. The terminal strip is further complicated by the necessity of incorporating two addi tionally separately formed elements, the cylindrical retention spring (not shown) identical to that employed in the present invention, which essentially surrounds that portion of the cylindrical socket intermediate of rim 22 and the bus strip 10. In which case, a cord or flattened portion of the cylindrical spring spans the interior of socket 16 to the extent permitted by opening 18. Further, a cylindrical contact spring 24 having a lance 26 struck outwardly of the same is inserted within the cylindrical socket 16 until its bottom edge 28 abuts an internal bottom wall 13 of the cylindrical socket l6, lance 26 being sufficiently flexible to permit insertion within the cylindrical socket 16, but moving into the lower opening 20 within the socket to lock the contact spring in place. The presence of the contact spring 24 insures electrical interconnection between the inserted male terminal pin and the female socket 16 receiving the same.

From the description of the prior art terminal strip to the extent described above, and when taken in conjunction with the teachings of Gagnier et al. U.S. Pat. No. 2,513,305, it can be appreciated that in the manufacture of the terminal strip which forms the principal component of the prior art terminal junction module, the cost of the terminal strip is relatively high due to the necessity for the screw machined cylindrical socket 16, the need of machining retention flange 14, rim 22, the bottom wall 30 and the creation of the openings 18 and 20, all these operations being performed separately after screw machining. Further, the cylindrical socket 16 must in itself be brazed at 18 to the terminal strip 10 at each opening 12, to create the desired cluster of sockets carried by a common metallic bus strip.

The present invention is directed to an improved, low cost terminal junction module and, in particular, to a stamped and formed terminal strip for such a module which includes a cluster ofspaced parallel aligned electrical contact sockets and in which the terminal strip is unitary with the exception of concentrically positioned pin retention spring, which embrace respective sockets.

Specifically, a cluster of integral, aligned stamped and formed electrical contact sockets, each of which is adapted to receive a cylindrical contact terminal pin and each having a transversely extending recess, comprises a metallic bus strip carrying a plurality of circular openings at spaced apart locations along the length of the same with each of the openings being defined by a drawn lip which extends outwardly of the bus strip on one side thereof. Each cylindrical contact socket is associated with a respective opening, is in axial alignment therewith and has a leading end which is spaced from the respective opening on the side of the bus strip carrying the drawn lip. Each socket is connected to the strip by a connecting strap extending from one side of the socket to a side edge of the strip, with the connecting straps of the adjacent sockets being connected to the opposite side edges of the strip. Each of the sockets has an opening in its side wall intermediate of its ends and a terminal pin retention spring surrounds each socket and has a contact retainer portion extending as a cord across the opening for engagement with a terminal pin recess to prevent withdrawal of the same after insertion. An integral supporting leg extends from the leading edge of each socket towards its respective opening with the leg terminating substantially against the edge of the adjacent lip, whereby upon full insertion of a contact pin into an associated socket, the contact retainer portion of the retention spring enters the recess in the pin and any tensile force applied in the direction of removal is effectively transmitted to the socket body and through the leg to the bus strip to the lip to prevent deformation of the socket during attempted withdrawal of the inserted terminal contact pin.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional, perspective view of a prior art terminal strip.

FIG. 2 is a sectional elevational view of a portion of the prior art electrical contact socket of FIG. 1, showing the inserted contact spring within the socket.

FIG. 3 is an exploded, perspective view of a terminal junction module incorporating the improved terminal strip of the present invention with a portion of the module housing broken away.

FIG. 4 is a plan view of a portion of the terminal strip of the present invention during stamping and forming of the same from metal strip stock.

FIG. 5 is a sectional view of the terminal strip of FIG. 4 taken about line 5-5.

FIG. 6 is an end view, partially broken away, of the terminal strip illustrated in FIG. 3.

FIG. 7 is an end view, partially in section, of a terminal strip of the present invention and illustrating in broken lines an inserted male terminal contact pin.

Referring to FIG. 3, the improved unitary, stamped and formed terminal strip of the present invention is supported within a terminal junction module housing 102 formed of a suitable rigid insulating material such as epoxy, the housing being generally of rectangular configuration and having a recess or opening 104 within one end of the same, the recess terminating in a flat bottom 106. The housing carries a plurality of aligned, spaced cylindrical contact cavities 108 which extend, in this case, downwardly towards the bottom of the housing. The socket cavities 108 number four in this case, although only two are visible. The present invention is directed to the improved terminal strip 100 which is stamped and formed from metal strip material having high electrical conductivity and being formed preferably of a copper alloy. A thin rectangular metallic bus strip 110 is provided with a plurality of circular openings 112 which are defined by drawn lips 114, the drawn lips extending downwardly and away from one side of the metallic bus strip 110. Integral stamped and formed cylindrical contact sockets 116 are in axial alignment with respective openings 112, each socket 116 having a leading end 118 which is spaced from its respective opening 112, the distance being defined by the effective axial length of a connecting strap 120 which extends from one side of each socket to a side edge of the metallic bus strip 110. Thus, in the FIG. 3, the first and third socket 116 from the left are connected by means of straps 120 to edge 122 of the bus strip 110 while the second and third cylindrical sockets 116 are connected by straps 120 to edge 124 of the bus strip. It is noted that the openings 112 are not in longitudinal alignment, but that the adjacent openings are longitudinally offset from each other for the purpose of permitting maximum density to the sockets, while permitting extraction tools to enter the smaller holes 126 adjacent respective openings 112 for releasing the cylindrical retention springs 128, which are concentric with and surround the cylindrical sockets 116,, rings 128 being illustrated in FIG. 3 as mounted on the two right hand sockets only. To release the male contact pin, such as pin 130, FIG. 7, permitting the pin to be withdrawn axially from a respective pin insertion hole 114, the pin structure, the insertion mode, the cylindrical retention spring and the tool for releasing the inserted pin from the spring are quire similar to that illustrated in FIG. 3 of the Gagnier et al. U.S. Pat. No. 2,513,305.

In that respect, each of the sockets 116 is provided with a rectangular opening 132 intermediate of its ends, and the terminal pin retention spring 128, which is generally cylindrical in form and provided with an inclined slot 134 permitting it to expand and contract, is further provided with a depressed or flattened wall portion 136, which extends as a chord across opening to axially locate and retain terminal pin retention spring 128 on socket 106 and further prevent withdrawal of a male terminal contact pin 130 after full insertion of the same, FIG. 7. Each of the pin retention springs 128 is characterized by the depressed portion 136 which extends within opening 132, having positioned axially adjacent thereto, a raised or protruding wall portion 138 and in order to separate the pin 130 from the socket 116, a pointed tool 'of the type shown in US. Pat. No. 2,513,305, is inserted within opening 126 of bus strip 110, into the raised portion 138 of the spring via opening 140. This permits the pin to lift the depressed section 136 forming the chord across the opening 132 from the chord receiving groove or recess within the pin, this lifting being achieved by circumferential expansion of the spring due to the resiliency of the same, as provided by the inclined slot 134. For a full understanding of the pin retention and release principle, reference may be had to US. Pat. No. 2,5 13,305.

One aspect of the present invention relates to the provision of integral means for insuring a positive frictional engagement and low resistance interconnection between the inserted pin 130 and the socket 116 receiving the same. In this respect, by reference to FIG. 7, it is noted that the inserted pin carries at its lower end a reduced diameter portion 140 which is received within a reduced diameter portion 144 of the socket. The lower portion 144 of the socket is slotted at 146 to permit its formation by stamping and forming of small diameter with some resiliency. This permits the inserted end 140 of the male pin 130 to expand the small diameter portion 144 receiving the same slightly and permit frictional gripping of this end of the pin 130 by the socket 116. Opening 146 is generally diamond shaped in configuration. A tapered portion 148 connects the main portion 150 of the socket to the reduced diameter terminal portion 144. On the opposite side of the diamond shaped opening 146, there is provided an elongated slot 150 of rectangular configuration to further facilitate the frictional gripping of the inserted end 142 of the male terminal contact pin 130 by the socket.

It would be assumed that supporting the cylindrical socket l 16 in axial alignment with its pin receiving hole 112 by means of a connecting strap to one side of the socket, would constitute a structurally unstable assembly which would be subject to ready destruction or deformation by forces acting through the inserted male terminal contact pin. In the present invention, a highly stable connection is achieved in spite of the use of a single connecting strap 120 for each socket. An integral supporting leg 152 extends from the leading edge 118 of the socket 116 and, in particular, the large diameter main wall portion 150 of the same, the supporting leg 152 extending toward its respective opening 112, terminating substantially adjacent the edge of the lip 114 which defines the opening. This relationship and the effect of the same may be best seen by reference to FIG. 6 wherein the edge 154 of leg 150 terminates just short of, and faces, the edge 156 of lip 114. Since the improved terminal strip of the present invention is, with the exception of the applied retention spring 128 which embraces the main body portion 150 of socket 1 16, en tirely stamped and formed of metal strip stock and thus, retrograde or removal forces acting through the inserted male terminal contact pin 130 on the pin receiving socket 1 16, would tend to direct the force axially through the window or opening 132 which receives the chordal depressed wall portion 136 of the spring, this force tending to swing the socket 1 16 in an arc about its connecting strap 120 which is on the side of the socket opposite that of the applied extraction force. However, in the unitary construction of the present invention the supporting leg 26 which is in alignment with the opening 132 and therefore in alignment with the extraction force acting upon the socket 116, makes ready contact between its upper edge 154 and the edge 156 of lip 114 restricting flexing of the supporting arm and insuring that any extraction force is taken up immediately by the rigid peripheral lip 114 of the metallic bus strip 110 over a considerable surface area. Thus, regardless of the fact that the socket is eccentrically loaded and the fact that the tensile pull on the pin tends to cock it relative to its normal axis, the leg 152 functions to transmit this tensile pull directly to the bus strip and prevent damage to the socket. Excessive removal force would tend to totally destroy the socket in the absence of the contact between the leg and the metallic bus strip in the area of the pin insem'on hole 112 and, in particular, by the downtumed lip 114 whose portion faces and is normally spaced only slightly from leg 152.

The manner in which the terminal strip of the present invention is manufactured in continuous strip form by the simple expedient of stamping the blanks for the contact sockets 116 on each side of the remaining central portion of the strip which forms the metallic bus strip 110, may be seen by reference to FIGS. 4 and 5. The sockets are stamped alternately from one side to the other, to permit close longitudinal spacing of the holes 112 and sockets 116, and the holes 112 are laterally offset from the longitudinal center line to further facilitate close spacing and maximum density of the terminals for the terminal junction module formed thereby. Openings 112, 126, 132, 146 and may be stamped simultaneously and at the same time the excess material may be cut away to define edges 122 and 120 prior to bending the sockets 116 inwardly toward each other and towards the face of the metallic bus strip 110 from which the drawn lip 114 extends. The

connecting straps are oblique or inclined, due to the fact that the diameter of the sockets is less than the width of the bus strip, the sockets alternating from side to side but extending parallel to each other and at right angles to the longitudinal plane of the metallic bus strip 1 10 supporting the same.

After stamping and forming in the manner illustrated in FIG. 1, the improved terminal strip 100 is inserted within housing 102. With the retainer springs 128 embracing respective sockets 116, the sockets are inserted within the passageways 108 receiving the same, and means (not shown) is provided for insuring retention of the terminal strip within the non-conductive housing 102, thus forming, in this case, a module constituted by four sockets to receive individually, four male terminal contact pins 130.

From the above, it is readily seen that there is substantial reduction in manufacturing costs without sacri fice of perfonnance or durability, with the reduction in cost being achieved by virtue of the fact that the number of parts making up the module is reduced constituting only the strip, the housing and the number of retainer springs equal to the sockets carrying the same as opposed to the prior machine formation requiring a flat plate, a screw machine socket, the necessity of brazing the same to the flat plate at each socket location, and a contact spring in addition to the retention spring for each socket. Both manufacture and assembly operations are simplified as compared with the prior art.

Changes in construction will occur to those skilled in the art, and various apparently different modifications and embodiments may be made without departing from the scope of the invention. The matters set forth in the foregoing description and accompanying drawings are offered by way of illustration only.

What is claimed is:

1. A terminal strip in the form of a cluster of integral, aligned electrical contact sockets, each of said sockets being adapted to receive a cylindrical contact terminal pin, said terminal strip comprising:

a metallic bus strip,

a plurality of circular openings within said strip at spaced-apart locations along the length thereof,

a stamped and formed cylindrical contact socket associated with each of the said openings, each of said sockets being in axial alignment with respective openings and having a leading end which is spaced from its respective opening on one side of said bus strip, each socket being connected to said strip by a connecting strap extending from one side of said socket to the edge of said strip, and an integral supporting leg extending from the leading end of each socket toward its respective opening and terminating adjacent thereto, and

terminal pin retention means carried by said socket for retaining a contact terminal pin within said socket upon insertion thereof, said supporting leg contacting the edge of the bus strip adjacent said opening to resist deformation of said socket body in response to pin extraction forces applied axially to said pin to extract the same 2. The terminal strip as claimed in claim 1, wherein; each cylindrical contact terminal pin includes a transversely extending recess, each of said sockets has an opening in its side wall intermediate of its ends, a terminal pin retention spring surrounds each socket and has a contact retaining portion extending as a chord across said opening and received within said pin recess, and said socket opening is in longitudinal alignment with said supporting leg to readily resist deformation of said socket as a result of pin extraction forces 3. The terminal strip as claimed in claim 1, wherein said connecting straps of adjacent sockets are connected to opposite side edges of said strip.

4. The terminal strip as claimed in claim 2, wherein the connecting straps of adjacent sockets are connected to opposite side edges of said strip.

5. The terminal strip as claimed in claim 1, wherein said circular openings within said metallic bus strip are each defined by a drawn lip extending therearound and away from said bus strip to the same side of said strip as that carrying said sockets and wherein, the edge of each integral supporting leg and a portion of a respective li are in face-to-face confrontation.

7. e ternunal strip as claimed in claim 4, wherein said circular openings within said metallic bus strip are each defined by a drawn lip extending therearound and away from said bus strip to the same side of said strip as that carrying said sockets and wherein, the edge of each integral supporting leg and a portion of a respective lip are in face-to-face confrontation.

8. A low cost, stamped and formed electrical terminal adapted to receive a cylindrical contact terminal pin having a transversely extending recess, said terminal comprising:

a metallic bus strip,

a circular opening within said strip formed by a drawn circular lip extending therearound and away from one side of said strip,

a stamped and formed cylindrical contact socket integral with said strip, said socket being in axial alignment with said strip opening and having a leading end which is spaced from said strip opening on said one side of said strip, said socket being connected to said strip by a connecting strap extending from one side of said socket to a side edge of said strip, said socket having an opening in its side wall intermediate of its ends,

a terminal pin retention spring surrounding said socket and having a contact retainer portion extending as a chord across said opening, and

an integral leg extending from the leading end of said socket towards said opening and terminating adjacent the edge of said lip and aligned therewith,

whereupon, after insertion of said contact pin into said socket to the extent where said spring retainer portions enter the recess in said pin, forces acting to remove said pin from said socket along said side wall socket opening and said retainer portion, in eccentric fashion, will be directly transmitted to said bus strip by said leg to resist socket deformation.

9. The terminal strip as claimed in claim 8, wherein each cylindrical socket includes a contact pin engaging portion beyond said socket side wall opening, said contact pin engaging portion being of reduced diameter and including at least one longitudinal slot to provide sufficient resiliency to afford frictional gripping of the end of said inserted contact pin. 

1. A terminal strip in the form of a cluster of integral, aligned electrical contact sockets, each of said sockets being adapted to receive a cylindrical contact terminal pin, said terminal strip comprising: a metallic bus strip, a plurality of circular openings within said strip at spacedapart locations along the length thereof, a stamped and formed cylindrical contact socket associated with each of the said openings, each of said sockets being in axial alignment with respective openings and having a leading end which is spaced from its respective opening on one side of said bus strip, each socket being connected to said strip by a connecting strap extending from one side of said socket to the edge of said strip, and an integral supporting leg extending from the leading end of each socket toward its respective opening and terminating adjacent thereto, and terminal pin retention means carried by said socket for retaining a contact terminal pin within said socket upon insertion thereof, said supporting leg contacting the edge of the bus strip adjacent said opening to resist deformation of said socket body in response to pin extraction forces applied axially to said pin to extract the same.
 2. The terminal strip as claimed in claim 1, wherein; each cylindrical contact terminal pin includes a transversely extending recess, each of said sockets has an opening in its side wall intermediate of itS ends, a terminal pin retention spring surrounds each socket and has a contact retaining portion extending as a chord across said opening and received within said pin recess, and said socket opening is in longitudinal alignment with said supporting leg to readily resist deformation of said socket as a result of pin extraction forces
 3. The terminal strip as claimed in claim 1, wherein said connecting straps of adjacent sockets are connected to opposite side edges of said strip.
 4. The terminal strip as claimed in claim 2, wherein the connecting straps of adjacent sockets are connected to opposite side edges of said strip.
 5. The terminal strip as claimed in claim 1, wherein said circular openings within said metallic bus strip are each defined by a drawn lip extending therearound and away from said bus strip to the same side of said strip as that carrying said sockets and wherein, the edge of each integral supporting leg and a portion of a respective lip are in face-to-face confrontation.
 6. The terminal strip as claimed in claim 2, wherein said circular openings within said metallic bus strip are each defined by a drawn lip extending therearound and away from said bus strip to the same side of said strip as that carrying said sockets and wherein, the edge of each integral supporting leg and a portion of a respective lip are in face-to-face confrontation.
 7. The terminal strip as claimed in claim 4, wherein said circular openings within said metallic bus strip are each defined by a drawn lip extending therearound and away from said bus strip to the same side of said strip as that carrying said sockets and wherein, the edge of each integral supporting leg and a portion of a respective lip are in face-to-face confrontation.
 8. A low cost, stamped and formed electrical terminal adapted to receive a cylindrical contact terminal pin having a transversely extending recess, said terminal comprising: a metallic bus strip, a circular opening within said strip formed by a drawn circular lip extending therearound and away from one side of said strip, a stamped and formed cylindrical contact socket integral with said strip, said socket being in axial alignment with said strip opening and having a leading end which is spaced from said strip opening on said one side of said strip, said socket being connected to said strip by a connecting strap extending from one side of said socket to a side edge of said strip, said socket having an opening in its side wall intermediate of its ends, a terminal pin retention spring surrounding said socket and having a contact retainer portion extending as a chord across said opening, and an integral leg extending from the leading end of said socket towards said opening and terminating adjacent the edge of said lip and aligned therewith, whereupon, after insertion of said contact pin into said socket to the extent where said spring retainer portions enter the recess in said pin, forces acting to remove said pin from said socket along said side wall socket opening and said retainer portion, in eccentric fashion, will be directly transmitted to said bus strip by said leg to resist socket deformation.
 9. The terminal strip as claimed in claim 8, wherein each cylindrical socket includes a contact pin engaging portion beyond said socket side wall opening, said contact pin engaging portion being of reduced diameter and including at least one longitudinal slot to provide sufficient resiliency to afford frictional gripping of the end of said inserted contact pin. 